Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors has continued to advance at a great pace. For example, the demands of higher resolution and lower power consumption have encouraged the further miniaturization and integration of these devices.
Noise in images captured by image sensor may manifest as white dots, for example, along with other noise patterns. The white dots may be caused by variation in barrier heights between pixels, and which may be due to electrons remaining in photodiodes of the pixels after precharge. The electrons may also introduce lag in the precharge operation and affect a full well capacity of the pixels. As such, it may be desirable to reduce white dot noise and the ancillary precharge lag and reduced full well capacity.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.